Conveyer screw



Patented-June 21, 1938 UNITED STATES PATENT OFFICE Application June 2'7, 1936, Serial No. 87,696 In Germany July 3, 1935 4 Claims.

This invention relates to conveyer screws, particularly for apparatus for the hot treatment of chocolate masses, comprising a helical member which is itself coreless, rotating in the gap bei tween a stationary casing and a stationary core with which it makes a close fit. In contrast with known conveyer screws of this type in which the central longitudinal section of the helical member is rectangular or square, according to the invention the frictional resistance to the operation of the screw and the power consumption required are reduced by reason that the central longitudinal section of the helical member is except for the leading portion, which is rectangular, that of a trapezium the shorter sides of which are normal to the casing and the core and the longer sides of which converge rearwardly. With such a construction only the leading short side of the trapezium and the curved areas of the leading portion extend close to the casing and the core, while the outer and inner sides of the trapezium are inclined away therefrom, so that without substantial diminution of the crosssectional area the friction is considerably reduced. This reduction of friction is the more important in' that even a helical member of powerful construction which is not stiffened by a core tends to be compressed axially, with simultaneous increase of its diameter, by the pressure due to the resistance offered by the mass to be conveyed, particularly in the case of a conveyer comprising a large number of convolutions, as the result of which the friction between the helical member and the casing wall is materially increased. This drawback heretofore experienced with coreless conveyer screws is now compensated for by the cross-sectional form of the helical member according to the invention.

This invention will be understood from the accompanying drawing in which the figure shows in central longitudinal section the construction according to the invention, a portion of the sta tionary core being broken away to show a portion of the helical member.

The numeral I denotes the stationary casing, 2 the stationary core, and 4 the helical conveyer member according to the present invention.

As pointed out above, in operation, the helical member 4 is rotated by any suitable means (not shown) between the stationary casing l and the stationary core 2, the direction of rotation being such as to force the material being conveyed, which may be specifically a chocolate mass, in the direction of the arrows shown in the drawing.

In the figure, in the interest of simplicity, the casing wall and the stationary core are shown as being of tubular form.

What I claim is:

1. In apparatus of the character described, an o'uter casing, a core, and a helical conveyer member adapted to rotate with respect to said casing and said core, the leading portion of said conveyer being adapted to span the space between said casing and said core, and the'remainder of said conveyer being spaced from said casing.

2. In apparatus of the character described, an

outer casing, a core, and a helical conveyer member adapted to rotate with respect to said casing and said core, the leading portion of said conveyer being adapted to span the space between said casing and said core, and the remainder of said conveyer being spaced from said core.

3. In apparatus of the character described, an outer casing, a core, and a helical conveyer member adapted to rotate with respect to said casing and said core, the leading portion of said conveyer being adapted to span the space between said-casing and said core, and the remainder of said conveyer being spaced from said casing and said core.

4. In apparatus of the character described, an' outer casing, a core, and a helical conveyer member adapted to rotate with respect to said casing and said core, the leading portion of said conveyer being adapted to span the space between said casing and said core, the normal section of said conveyer being a rectangle having two relatively short opposed sides in contact with said casing and said core, said rectangle on its rear relatively longer face merging into a trapezoid having a rear edge approximately normal to said casing and said core, and said rear edge being shorter than the edge merged into said rectangle. ARTHUR WINTERLICH. 

